This invention relates to a communication path monitoring system for a communication network that uses a link state routing protocol to determine the route of a communication path to be established and that uses a signaling protocol to establish the communication path, as well as to a communication network system composed of the communication network and the communication path monitoring system.
GMPLS (IETF, Internet-Draft, draft-ietf-ccamp-gmpls-architecture-07.txt, Eric Mannie et al., “Generalized Multi-Protocol Label Switching Architecture”) is one of techniques for controlling the communication quality of a communication network. This technique sets, by way of a signaling protocol such as GMPLS extended RSVP-TE (IETF, RFC 3473, L. Berger et al., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions”), an LSP (Label Switched Path), which is a virtual communication path, in a communication network composed of network devices such as a wavelength switch, a time division multiplexer and a packet switch.
In such a communication network, keeping track of the route and operational state of a communication path is important in order to enable the communication network's administrator or management system to make the communication network recover from a network failure.
An example of a method used in MPLS to keep track of the route and operational state of a communication path is disclosed by Cheenu Srinivasan et al., in “Multiprotocol Label Switching (MPLS) Traffic Engineering Management Information Base”, IETF, Internet-Draft, draft-ietf-mpls-te-mib-14.txt (hereinafter referred to as “the IETF Internet draft”). According to this technique, a network management system can obtain, from an MPLS router, the state of an LSP and the LSP's attribute information such as route information by using SNMP (Simple Network Management Protocol, IETF RFC 3416).
Disclosed by Aman Shaikh et al., in “An OSPF Topology Server: Design and Evaluation”, IEEE J. Selected Areas in Communications, vol. 20, No. 4, May 2002 (hereinafter referred to as “Shaikh et al.”) is a technique of checking the stability of route control in a large-scale network by capturing and collecting link state advertisements of OSPF (“OSPF Version 2”, IETF RFC 2328), which is an IP network routing protocol.
In networks that are actually run, various types of GMPLS switch and MPLS router are installed in mixed and varied manners.
The technique disclosed in the IETF Internet draft needs for GMPLS switches and MPLS routers to have an SNMP agent function and a management information base. In practice, however, GMPLS switches and MPLS routers do not always have the two because of development cost or other limitations. Then this technique cannot be applied.
Moreover, in what format information is stored in the management information base is not specified in the technique disclosed in the IETF Internet draft, and varies depending on the type of GMPLS switch or MPLS router employed. It is therefore necessary for a monitoring manager to even out the differences in format used to store information in the management information base. The monitoring manager has to develop, for each and every type of GMPLS switch or MPLS router it manages, software to even out the format differences, and developing the software costs money.
The technique disclosed in Shaikh et al. relates to analyzing a link state routing protocol in an IP network, and is not applicable to management of communication paths in a connection-oriented network such as one composed of GMPLS switches or MPLS routers.